This invention relates to the architecture of digital information processing equipment; and more particularly to the architecture of digital computers.
Typically, a manufacturer of digital computers produces not just one computer type; but instead, it produces several different varieties, or models. These models vary substantially in processing power and price. Basically the various models are needed because customer requirements vary widely. Thus, IBM has produced system 360 models 20, 30, 40, 50, 65, 75, and 90, and now produces system 370 models 125, 135, 138, 145, 148, 155, 158, and 168. All other major manufacturers of digital computers also produce several computer models.
In the past, the various computer models of any one particular manufacturer differed substantially from each other in their architecture. Compare for example, the architecture of the above IBM models 40 and 50 as illustrated at pages 221 and 297 of Microprogramming Principles and Practice, Samir S. Husson, Prentice-Hall Inc., 1970. Compare also the architecture of the NCR Century 100, 200, 300, or the architecture of the Burroughs 4800 and 6800. Each model has its own unique data paths, its own unique functional logic, etc.
From a design engineer's point of view these differences in architecture pose no problem; all that is relevant is whether each model meets its own functional requirements. But from a manufacturing point of view, each model essentially is a separate ensemble of unique parts. Thus, little or no economy is achieved through commonality in design, in fabrication, or in inventory or parts for the various models.
This dissimilarity between models can place very severe strains on a manufacturer's financial resources; because essentially separate design cycles, separate production facilities, and separate inventory need to be provided for each model. And typically, for any one model, these items can cost several million dollars.
Further, from an integrated circuit (IC) manufacturer's point of view, the problem is even more severe. It must supply IC's which meet the diverse functional requirements of the computer models from several computer manufacturers. And typically, no commonality in architecture exists between computer models from different manufacturers. Compare for example, the IBM 370 models to the Burroughs 6800.
Accordingly, a primary object of this invention is to provide an improved architecture for digital information processing equipment which uses "standardized" parts and is flexible enough to adapt to the different functional requirements of any computer model.